Filter devices of this type are prior art and are used in a wide variety of fields. In the prior art, such devices are especially widely used in applications for cleaning operating fluids such as hydraulic fluids, fuels or lubricants, coolants and the like. Since the filter devices form important system components, proper functioning and filter performance are a prerequisite for the smooth operation of the respective systems. Taking into consideration the fact that malfunctions, which may include damages and failures, may result in very high costs, the functional reliability of the filter devices represents a significant economic factor.